This method is unfortunately not open at present to English medical officers of health, being a breach of the Vivisection Act. It is only in those large towns and places where the local authority possesses an ice chamber in which to deposit suspected meat that any prolonged investigation can take place; the officer has usually to decide there and then; whereas in common justice to all parties it would be better for there to be a proper place for the meat to be taken to and there detained and a thorough and complete examination to be made.

SS

CHAPTER XL.

DISEASES OF ANIMALS RENDERING THEIR FLESH MORE OR LESS UNFIT FOR FOOD.

(460) Measles in the Pig and the Ox.

THIS is a parasitic disease, little cysts being scattered about the muscular system, each cyst containing the larval or hydatid stage of a tape-worm. The parasite is called the bladder-worm, or cysticercus cellulosa. A different species affects the pig to that of the ox, but the naked eye appearances and the distribution in each is very similar. The way in which these parasites gain access to animals is as follows:-A human being afflicted with tape-worm passes the segments of the mature tape-worm full of thousands of eggs. These eggs are in some way or other swallowed by pigs or oxen (or, as for that, by sheep), the eggs are hatched inside the body. The embryo when hatched makes its way into the tissues by the aid of a peculiar apparatus round its mouth consisting of six hooklets, and there develops not into a tape-worm but into the hydatid or bladder form. Nor will it further develop, save the animal is killed and the living hydatid pass into the human or other intestine, then it enters on its completed existence, and fastening by means of the hooklets, or in the hookless form by suckers, on to the mucous membrane, grows into a tape-worm many feet in length. Each joint of a tape-worm may contain as many as 53,000 eggs, so that if only a few joints of the tape-worm are eaten, and only a portion of the eggs hatched yet enormous numbers of hydatids may be formed. When the embryo arrives at its resting-place a cyst or bladder forms at the spot, in the centre of which the worm is coiled up; it is about

a third of an inch in its longest diameter, or from the size of a pea to that of a cherry in the retracted state, it is oval, but when the head and neck is extended it is bottle or gourd-shaped. The vesicle is filled with an albuminous, milky-coloured fluid, and in the retracted state exhibits a dense white spot at one point of its surface. Hydatids in pigs are specially to be looked for in the muscles of the tongue, the neck, and the shoulders; but hydatids may be found in the liver, kidney, brain, and many tissues in the body. During life the existence of measles is often detected, the pig is thrown down, a piece of wood is thrust across the jaws, and the tongue pulled outside the mouth, the organ is carefully examined underneath towards the root and the bridle where, if present, the cysts may be seen and felt, still their absence is not conclusive evidence that they do not exist elsewhere.

In the ox, the hydatid is to be looked for in the same situations as in the pig.

The naked eye appearances of measles (cysticercus bovis) in beef are represented in Plate VI., which has been drawn (natural size) from a specimen in the College of Surgeons' Museum (No. 123 in Catalogue). This cysticercus if taken into the human intestine may develop into the tape-worm known as the taenia medio-cannclata; neither the bladder- nor the tape-form are proIvided with hooks.

The diaphragm, the tongue, the superficial muscles of the shoulder, breast, loin, hip, or quarter, and the eyelids, are the special likely places. The heart, too, in the majority of cases is also affected.

Hydatids have a considerable power of resistance to both heat and cold, but they perish at a temperature of 170° F., and, of course, at the temperature of boiling water, so also a lengthened exposure to cold, or smoking will destroy them, and prolonged immersion in brine. Nevertheless, it is not safe to allow any measly meat to be sold, for it is never certain that such meat will be cooked properly, and the signs of death in such low animal forms are deceptive.

(461) Trichino-Trichinosis.

The trichina spiralis is a minute worm, parasitic in the muscular system of man and animals. The disease affects pigs and men,